Single step solution combustion synthesis of hexagonal WO₃ powders as visible light photocatalysts

To directly synthesise hexagonal tungsten oxide that has enhanced photocatalytic activity, we studied the solution combustion synthesis using oxalic acid as fuel. The experimental results indicated that fuel to oxidizer ratio is the key for the crystallite size of the powders which varied from 27.96 nm to 42.27 nm for the ratio of 1 and 5, respectively. Specific surface area of the WO₃ powder was measured as 17.5 m²/g produced with the fuel to oxidizer ratio of 1. Photocatalytic activity of obtained powders were investigated by methylene blue degradation under sunlight. The best photocatalytic degradation efficiency was found to be 98.95% within 60 min of the initial MB concentration for the powder synthesized with fuel to oxidizer ratio of 5. The band gap energies were estimated within the range of visible light having the value of 3.65 eV and 3.47 eV. So that, as synthesized powders were suitable to be used as visible light photocatalyst for wastewater treatment.